Organic compounds, and more specifically pharmaceuticals, are generally more stable when they exist as a solid or powder than when they exist in solution. As such, the shelf-life of a pharmaceutical stored in solution is generally shorter than the shelf-life of the pharmaceutical stored as a solid or powder. Since many pharmaceuticals are stored for extended periods of time before use, it is advantageous to have these pharmaceuticals remain active over the extended period of time. It is therefore desirable to store pharmaceuticals, over an extended period of time, as a solid or powder. This especially includes those pharmaceuticals that are ultimately reconstituted before being administered as a solution.
Lyophilization is routinely used in the preparation and storage of pharmaceuticals. In such applications, lyophilization is usually carried out by freezing a solution containing the pharmaceutical, followed by sublimation to provide the solid or powder essentially free of solvent. Lyophilization directly in a vial or ampule requires transfer of the reconstituted pharmaceutical from the vial or ampule to a syringe. As such, a syringe is especially useful for the lyophilization of an injectable medication since the medication is ultimately administered from the syringe. Lyophilization can be performed wherein a solution containing the pharmaceutical is lyophilized directly in a syringe. See, U.S. application Ser. No. 09/190,341. The lyophilized pharmaceutical (i.e., medication) can then be stored in the syringe wherein a diluent can be added to the syringe for reconstitution of the medication just prior to administration. The reconstituted medication can then be administered directly to the patient from the same hypodermic syringe in which the lyophilized medication had been stored.
Several problems exist in the packaging, shipment, and storage of a lyophilized pharmaceutical. Syringes are usually provided in an individual sterile package which is opened at the time of use. However, non-sterile matter (e.g., bacteria) from the environment may enter the syringe barrel through the proximal open end when the syringe is packaged. The pharmaceutical is displaced between the distal end of the syringe barrel, which is sealed, and the plunger tip, which creates a seal. As such, the pharmaceutical is usually contained within a sterile portion of the syringe barrel. The portion of the syringe barrel between the plunger tip and the proximal end, however, is open to the environment. Even though the syringe may be packaged in a sterile packaging system, non-sterile matter (e.g., bacteria) can be introduced in that portion of the syringe barrel during packaging and can survive (i.e., remain dormant) in the syringe barrel over the lengthy storage time.
Reconstitution of the lyophilized pharmaceutical can be accompanied by the entrance of any non-sterile matter (e.g., bacteria) present in the non-sterile portion of the chamber of the syringe barrel. This occurs because the plunger rod and the stopper may be drawn back and forth along the portion of the syringe barrel where non sterile matter was introduced. Each cycling of the stopper along the barrel provides potential for contamination of the contents contained within the syringe. The introduction of non-sterile matter (e.g., bacteria) into the chamber of the syringe barrel results in the syringe, and the lyophilized pharmaceutical contained therein, being discarded or recycled, or infecting the patient. The likelihood of the entrance of non-sterile matter is heightened when the reconstitution is accompanied by syringe-to-syringe mixing.
Because of the extremely high requirements for sterility and quality control, lyophilization of pharmaceuticals is a very expensive process. The process requires a significant amount of energy to sustain the proper freezing and vacuum conditions in a lyophilization chamber. It is also costly and time consuming to discard or recycle those syringes, and the lyophilized pharmaceutical contained therein, because of contamination. Moreover, serious medical risks exist when a medication that is not sterile is parentally administered to a patient. As such, a syringe assembly is needed that will maintain the sterility of the lyophilized product during packaging, shipment and storage.
The present invention is directed to a syringe assembly that maintains sterility, as well as to processes for their filling and use. The first syringe assembly includes a hollow barrel that has an interior wall. The interior wall defines a chamber that retains medication. The hollow barrel also includes a distal end and a proximal end. The distal end of the hollow barrel has a passageway that is in contact with the chamber. The proximal end of the hollow barrel has an aperture. The syringe assembly also includes a primary plunger tip that is slidably positioned, in fluid tight engagement, with the interior wall. The primary plunger tip has a receptor to engage an engager of an elongated tip plunger rod. The syringe assembly also includes a secondary plunger tip that is slidably positioned, in fluid tight engagement, with the interior wall. The secondary plunger tip also has a receptor to engage an engager of a tip plunger rod. The secondary plunger tip is disposed between the primary plunger tip and the proximal end of the hollow barrel. The syringe assembly also includes a tip plunger rod, which facilitates operation of the secondary plunger tip, engaged to the secondary plunger tip.
The second syringe assembly is similar to the first syringe assembly but further includes an elongated tip plunger rod with an engager that is configured to engage the receptor of the primary plunger tip. The elongated tip plunger rod facilitates the operation of the primary plunger tip. The third syringe assembly is the first syringe assembly further including a medication disposed between the primary plunger tip and the distal end of the hollow barrel.
The present invention also provides a process for providing a lyophilized medication (i.e., lyophilizate) in a syringe assembly. The process includes providing a third syringe assembly and lyophilizing the solution in the chamber to provide a lyophilizate. The process also includes inserting the primary plunger tip that is slidably positioned, in fluid tight engagement, with the interior wall. The primary plunger tip has a receptor to engage an engager of an elongated tip plunger rod. The primary plunger tip is disposed between the lyophilizate and the proximal end of the hollow barrel. The process also includes inserting a secondary plunger tip that is slidably positioned, in fluid tight engagement, with the interior wall. The secondary plunger tip is engaged to a tip plunger rod. The secondary plunger tip is disposed between the primary plunger tip and the proximal end of the hollow barrel.
The present invention also provides a process for reconstituting a medication in a syringe assembly. The process includes providing a second syringe assembly. The second syringe assembly also includes a medication that is disposed between the primary plunger tip and the distal end of the hollow barrel. The second syringe assembly also includes a discharge assembly or cannula (e.g., a needle) in fluid transport connection with the passageway. The secondary plunger tip is disposed between the primary plunger tip and the proximal end of the hollow barrel. The process also includes removing the secondary plunger tip from the hollow barrel and placing the discharge assembly in contact with a diluent. The process also includes urging the primary plunger tip proximally and away from the distal end of the hollow barrel. As the primary plunger is urged away from the distal end of the hollow barrel, the diluent is urged through the discharge assembly and through the distal end of the hollow barrel. As such, the diluent comes into contact with the medication thereby effectively reconstituting the medication. Alternatively, the distal end of a second syringe assembly can be connected to a third syringe containing a diluent by means of a luer-lock coupler and the diluent can be discharged into the second syringe where it comes in contact with the medication. The mixture of diluent and medication can then be pushed back and forth between the two syringes until the contents are thoroughly mixed. The contents can then be drawn into one of the syringes, the coupler and other syringe can be removed, and a discharge assembly or cannula (e.g., a needle) can be attached to the syringe with the contents.